John, visit
www.trixbox.com. It's LAMP but mostly configured through a GUI. It has every imaginable feature. And it's free unless you want to pay extra for the pro version with better support and more features. 64 simultaneous calls is no problem for either version and you can do it using VOIP or pots lines.
"... They ne'er cared for us
yet: suffer us to famish, and their store-houses
crammed with grain; make edicts for usury, to
support usurers; repeal daily any wholesome act
established against the rich, and provide more
piercing statutes daily, to chain up and restrain
the poor. If the wars eat us not up, they will; and
there's all the love they bear us."
-- Shakespeare: Coriolanus, Act 1, scene 1
